1. Technical Field
The present invention relates generally to busbar units and technologies in electric motors in which busbar units are employed.
2. Description of the Related Art
In recent years, electric motors are being exploited as a power source for a variety of automobile machinery such as power steering and throttle valves. In the motors, electronic parts of various kinds are mounted on circuit boards in order to realize high-precision control. Given that long-term, precision operation under various environments is being demanded of automobiles, advanced reliability is in turn being demanded of motors as one component of automobile machinery.
In electric motors, electronic parts such as coil terminal wires and sensor elements are connected to a busbar or circuit board provided on the coil end of an armature. In the electric motor taught in Japanese Unexamined Pat. App. Pub. No. H10-14153, for example, coil terminal wires and a speed detecting sensor are connected to a board on which a support piece is mounted, and additionally, a connector jack is joined onto the board, wherein connection between the board and lead wires for an external power source is made via the connector, and signals from the speed-detecting sensor are brought to the exterior via the connector as well.
In recent years, motor-employing electric power steering (EPS) has been attracting attention as an efficient system in that engine power loss is slight compared with hydraulic power steering, in which engine output is directly transferred to the steering fluid. Motors employed in EPS include machines exploited as a power source for fluid-delivering pumps that operate with the motor interior being filled with fluid. Implementations in which the motor interior is fluid-filled, however, risk giving rise to electrical hazards such as short circuiting should metal powder get mixed into the fluid for some reason.
Moreover, with electric motors such as set forth in the foregoing reference, in implementations in which the pins inside the connector jack are joined directly to the circuit board, the force acting on the pins when the jack is coupled to and decoupled from an external plug is transmitted directly to the circuit board, which runs the risk that the stress arising in the coupling/decoupling force will lead to damage to the joint between the pins and the circuit board, or to cracks in the circuit board.